Development of an ICRH antenna system at W7-X for plasma heating and wall conditioning

Schweer, B.; Ongena, J.; Borsuk, V.; Birus, D.; Bozhenkov, S.; Bardawil, D. Castano; Durodié, F.; Hartmann, D.; Hollfeld, K. P.; Kallmeyer, J. P.; Křivská, A.; Louche, F.; Messiaen, A.; Neubauer, O.; Offermanns, Guido; Satheeswaran, G.; Schoor, M. Van; Vervier, M.; Wolf, R. C.

doi:10.1016/j.fusengdes.2017.05.019

Cited by 15 publications

(13 citation statements)

References 1 publication

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“…The next step to upgrade the current wall conditioning strategy will be achieved by expoloitation of a new conditioning tool based on Ion Cyclotron Resonance Heating System [24]. It is expected that Ion Cyclotron Wall Conditioning (ICWC) may be more effective for density control than currently used ECWC, as already demonstrated on WEGA [25].…”

Section: Discussionmentioning

confidence: 99%

Wall conditioning at the Wendelstein 7-X stellarator operating with a graphite divertor

Goriaev

Wauters²,

Brakel

et al. 2020

Phys. Scr.

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Wall conditioning plays an important role in achieving record plasma performance on superconducting stellarator Wendelstein 7-X (W7-X) by controlling plasma density and keeping low level of impurities. The development of the optimal wall conditioning strategy is of high importance for successful operation of W7-X with graphite divertor. The current strategy consists of initial wall conditioning applied prior to physics experimental program and wall conditioning techniques executed during plasma operation phase. The combination of baking and glow discharge cleaning (GDC) provides fast start of reliable plasma operation. Regular boronisation opens a new operational window of high plasma densities above 1*10 20 m -3 . Strong wall fueling remains however one of the main issues preventing plasma density control. A reliable solution is provided by application of He ECRH pulse trains which are optimised to maximise fuel removal.

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Section: Discussionmentioning

confidence: 99%

Wall conditioning at the Wendelstein 7-X stellarator operating with a graphite divertor

Goriaev

Wauters²,

Brakel

et al. 2020

Phys. Scr.

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“…ECRH conditioning plasmas in stellarator W7-X efficiently interact with the divertor area and are therefore more similar to divertor conditioning by tokamak plasma rather than to ECWC in a tokamak. A comparison of ICWC operation in a tokamak and conditioning by IC heated plasmas in W7-X waits for first results with the W7-X ICRH antenna system, currently under construction [68]. The available dedicated experimental comparisons show that ICRF plasma removes more or faster than ECRH plasma, both in tokamak TEXTOR [69] and in stellarator WEGA [70].…”

Section: Discussionmentioning

confidence: 99%

Wall conditioning in fusion devices with superconducting coils

Wauters¹,

Borodin

Brakel

et al. 2020

Plasma Phys. Control. Fusion

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Wall conditioning is essential in tokamak and stellarator research to achieve plasma performance and reproducibility. This paper presents an overview of recent conditioning results, both from experiments in present devices and modelling, in view of devices with superconducting coils, with focus on W7-X, JT-60SA and ITER. In these devices, the coils stay energised throughout an experimental day or week which demands for new conditioning techniques that work in presence of the nominal field, in addition to the proven conditioning methods such as baking, glow discharge conditioning (GDC) and low-Z wall coating through GDC-plasma, which do not work under such condition. The discussed techniques are RF conditioning without plasma current, both in the ion cyclotron and electron cyclotron range of frequencies, and diverted conditioning plasmas with nested magnetic flux surfaces.

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“…Similar to the W7-X antenna matching system, 17 the antenna is tuned first by using a pre-matching capacitor connected to the top of the antenna strap and fed by a center tap. The pre-matching capacitor CA is a Comet CV2C 1000 variable capacitor.…”

Section: Ion Cyclotron Range Of Frequency Systemmentioning

confidence: 99%

The upgraded TOMAS device: A toroidal plasma facility for wall conditioning, plasma production, and plasma–surface interaction studies

Goriaev

Wauters²,

Möller

et al. 2021

Review of Scientific Instruments

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The Toroidal Magnetized System device has been significantly upgraded to enable development of various wall conditioning techniques, including methods based on ion and electron cyclotron (IC/EC) range of frequency plasmas, and to complement plasma-wall interaction research in tokamaks and stellarators. The toroidal magnetic field generated by 16 coils can reach its maximum of 125 mT on the toroidal axis. The EC system is operated at 2.45 GHz with up to 6 kW forward power. The IC system can couple up to 6 kW in the frequency range of 10 MHz-50 MHz. The direct current glow discharge system is based on a graphite anode with a maximum voltage of 1.5 kV and a current of 6 A. A load-lock system with a vertical manipulator allows exposure of material samples. A number of diagnostics have been installed: singleand triple-pin Langmuir probes for radial plasma profiles, a time-of-flight neutral particle analyzer capable of detecting neutrals in the energy range of 10 eV-1000 eV, and a quadrupole mass spectrometer and video systems for plasma imaging. The majority of systems and diagnostics are controlled by the Siemens SIMATIC S7 system, which also provides safety interlocks.

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Development of an ICRH antenna system at W7-X for plasma heating and wall conditioning

Cited by 15 publications

References 1 publication

Wall conditioning at the Wendelstein 7-X stellarator operating with a graphite divertor

Wall conditioning at the Wendelstein 7-X stellarator operating with a graphite divertor

Wall conditioning in fusion devices with superconducting coils

The upgraded TOMAS device: A toroidal plasma facility for wall conditioning, plasma production, and plasma–surface interaction studies

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